The vitamin K-dependent, enzymatic carboxylation of some Glu residues allows the modified protein to bind calcium.N- and O-glycosylated. Partial (70%) N-glycosylation of Asn-371 with an atypical N-X-C site produces a higher molecular weight form referred to as alpha. The lower molecular weight form, not N-glycosylated at Asn-371, is beta. O-glycosylated with core 1 or possibly core 8 glycans.The iron and 2-oxoglutarate dependent 3-hydroxylation of aspartate and asparagine is (R) stereospecific within EGF domains.May be phosphorylated on a Ser or Thr in a region (AA 25-30) of the propeptide.